UPDATED: Sarepta shares rocket up on stellar muscular dystrophy trial results

Sarepta Therapeutics ($SRPT) has managed to wow analysts once again with its promising new treatment for Duchenne muscular dystrophy, posting stellar improvements in the walking ability of a set of boys afflicted with the rare disorder. Among a small group given the highest dose of eteplirsen, patients were able to outpace the placebo arm by 89.4 meters in a six-minute walk test. 

Shares of the Cambridge, MA-based biotech, already stoked by earlier efficacy results, soared a whopping 162% by late morning as investors eagerly bought into the notion that Sarepta may be poised to gain an early approval of the drug. But the day was marred by the separate announcement that the government has killed its contract to develop a new therapy for the ebola virus.

Sarepta's exon-skipping approach addresses the cause of the disease: A genetic mutation that eliminates dystrophin. In their mid-stage study the company reports that the drug triggered a "statistically significant increase (p≤0.001) in dystrophin-positive fibers to 47.0% of normal." 

Lee Sweeney, chairman of physiology at the University of Pennsylvania's Perelman School of Medicine, told Forbes' Matthew Herper that eteplirsen looked "incredibly promising. They (patients) don't ever improve once they start going down. The fact you can improve them is not something that happens normally. That's not random."

Herper, though, also sounded a note of caution about the tiny trial, which enrolled only 12 patients. And two of the patients in the low-dose arm declined badly, possibly because the disease had already progressed too far. The FDA might not be willing to push ahead with a quick approval once they consider those factors.

- here's the press release on the data
- get the release on the ebola contract
- here's the story from Forbes
- see the report from Reuters